1. Field of the Invention
The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor having a highly waterproofing surface and a high resistance to mechanical abrasion.
2. Description of the Related Art
Electrophotographic photoreceptors are required to have predetermined sensitivities, electronic properties and optical properties as well as resistance to abrasion and readiness to cleaning. Since the photoreceptors are susceptible to scratches due to development with toner, abrasions with sheets and cleaning members, their resistance to abrasion is very important. On the other hand, the readiness to cleaning is a property determining ease of removing the toner adhered to and remaining on the surface of the photoreceptor and required to be higher in order to produce sharp images causing no blurring of images, particularly under high moisture.
The image blurring phenomenon tends to occur when the surface resistivity of the photoreceptors is markedly reduced at a high humidity owing to existing of a hydrophilic and hygroscopic film on the surface, adsorption of ions to the surface due to the corona charges thereon, or attaching of sheet dust tot he surface upon transferring operation.
The photoreceptors have differences in potential between light parts and dark parts on their surfaces after charging and exposing them to lights. When the photoreceptors have a hydrophilic surface, the charges flow from high potential parts to low potential parts across the interfacial regions therebetween so that the potentials at the interfacial regions are averaged to give no reproduction of sharp contours in images resulting in the image blurring and spread.
The surfaces of conventional inorganic and organic photoreceptors have problems on the resistance to abrasion and the readiness to cleaning so that various methods have been proposed to provide a protective layer.
There have been reported hydrolyzates of silane coupling agents as materials for the protective layers. In such techniques, silane compounds having an alkoxy group, an amino group and/or a methacryl group such as methyl trimethoxysilane, vinylchlorosilane and .gamma.-glycidoxypropyl trimethoxysilane have been used.
Recently, an attempt has been proposed to allow the protective layers to contain fluorinated silane coupling agents [Japanese Patent Kokai (Laid-open) No. 61-205950 (1986)].
In this attempt, the protective layers comprises a thermoplastic resin, or thermosetting resin mixed with fluorine compounds, or fluorinated silane coupling agents.
As described in prior patents, the processes using hydrolyzates of silane coupling agents as materials for the protective layers resulted in the layers having a resistance to abrasion, but a poor readiness to cleaning, while conversely those using fluorinated silane coupling agents could achieve some improvement in the readiness to cleaning, but caused a problem on the resistance to abrasion due to a lower hardness of the resins and simple blending rather than reacting with the fluorinated silane coupling agents.